The Department of Education is preparing space for a whopping 100,000 students in charter schools within four years — quadrupling the number of kids in charters today, according to a DOE personnel document.

That would mean nearly one in every 10 city public-school students could be attending a charter as early as 2013.

Asked at a Harlem event about his goals for charter-school growth, Schools Chancellor Joel Klein said, “In an ideal world parents will have . . . great choices for their kids.”

He added, “I think this debate about what the label on the school is, is a debate about politics and special interests and everything else.”

The teachers union and its allies are campaigning to slow the expansion of charters — privately managed schools mostly exempt from union and other bureaucratic rules.

Under Mayor Bloomberg and Klein, the number of charter schools will have grown from 17 in 2002 to at least 99 this September, with about 32,500 students enrolled.

But a DOE spokeswoman downplayed the 100,000 figure, saying the city would seek to enroll a minimum of 50,000 students in charters by 2012, with enough seats available to serve twice that amount.

She cautioned that a state legislative cap on the number of charter schools — 200 statewide — could impede that growth.

The city’s charter expansion plans were buoyed after prominent educational philanthropist Eli Broad announced yesterday that he had agreed to donate a combined $2.5 million to two charter-management companies — Uncommon Schools and Success Charter Network.

Broad also endorsed continuing mayoral control of the schools. The state law that gave Bloomberg authority over the schools expires on June 30, and the teachers union and other critics are fighting to loosen City Hall’s grip over education.

“I think mayoral control is vital. There’s no question in my mind that without mayoral control in the last seven years this city’s school system would not have made the gains it’s made,” said Broad, whose foundation has pumped $30 million into Big Apple school reforms.

“I regret that Los Angeles, where I live, does not have mayoral control. I look across America and I see 14,000 to 15,000 school boards frankly made up of political wannabes, well-meaning parents, people representing labor organizations — many of whom think they’re in the business of giving jobs away rather than educating kids,” he said.

Broad said major improvements in urban education have come only when mayors have been given direct control, and he suggested that a dramatic increase in New York City charters wouldn’t happen without Bloomberg in charge.

“People say it’s taking money away from the public-school system,” he said. “That’s nonsense. These [charters] are public schools. They’re laboratories for success that others can emulate within a public-school system. So I’m a very strong believer in mayoral control.”